Michelle Chu, a Boston EMS dispatcher, was in the middle of training today on how to handle high-stress situations when she found herself in the middle of one, coaching a Hyde Park man over the phone as he delivered his wife’s baby.

Chu talked the new father through the delicate process of delivery while her training instructor, EMT Mike Mynahan, listened over her shoulder, Boston Emergency Medical Services said in a statement.

“There’s always that first surge of adrenaline,” said Chu, an EMT who has delivered babies before while working in the field. “But once you start to realize you have a task to accomplish, this sort of calm comes over you.”

Explaining to someone else how to deliver a baby, especially someone with no medical experience, can be much harder than delivering a baby yourself, she said in a telephone interview.

When she was originally training to be an EMT, Chu’s instructors told her she was being too nice at times and needed to take control. Today she heeded that advice, she said. With an understandably agitated father on the phone, Chu knew she had to take control — and calm him down.

“Your most important job as someone who is on the phone for 911 is to be the voice of reason,” Chu said. “You have to be reassuring but authoritative.”

After the father successfully delivered the baby, Chu congratulated the mother and stayed on the phone with the couple until an ambulance arrrived.

The best moment, she said, was when she finally heard the baby crying in the background.